CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $) In Thousands	Noncontrolling Interest [Member] Series D Preferred Stock [Member]	Noncontrolling Interest [Member] Series E Preferred Stock [Member]	Noncontrolling Interest [Member]	Preferred Stock [Member]	Common Stock [Member] Common Class A [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2008			$ 1,598	$ 10	$ 3,308	$ 9,792,371	$ (3,364,927)	$ (315,529)
Impact of adoption of new authoritative OTTI guidance, net of taxes							(229,670)	229,670	229,670
Impact of adoption of new authoritative embedded derivative guidance, net of taxes							0	0	0
Net income (loss) attributable to XL Group plc								74,991	74,991
Change in net unrealized gains (losses) on investments, net of tax							2,376,556		1,126,887
Change in net unrealized gains (losses) on affiliate and other investments, net of tax							14,464		14,464
Change in OTTI losses recognized in other comprehensive income, net of tax							(123,343)
Change in underfunded pension liability							(3,427)		3,427
Change in value of cash flow hedge							438		(438)
Change in net unrealized gain (loss) on future policy benefit reserves							6,554		6,554
Foreign currency translation adjustments							180,888		180,888
Issuance of ordinary shares					114	741,177
Exercise of stock options					0				0
Buybacks of ordinary shares					(1)	(625)
Transfer to non-controlling interest in equity of consolidated subsidiaries				0		0
Dividends on preference ordinary shares						(42,126)		(38,073)
Gain on redemption of Redeemable Series C preference ordinary shares								211,816	211,816
Dividends on ordinary shares						(68,389)		(68,415)
Exercise of stock options, net of tax						0
Share based compensation expense						52,280
Non-controlling interests			(104)						(104)
Non-controlling interest share in change in AOCI			811
Transfer from Series E preference ordinary shares and additional paid in capital			0
Issuance of Series D preference ordinary shares			0
Purchase of preference ordinary shares	0	0
Balance at Dec. 31, 2009			2,305	10	3,421	10,474,688	(1,142,467)	94,460	9,432,417
Impact of adoption of new authoritative OTTI guidance, net of taxes							0	0	0
Impact of adoption of new authoritative embedded derivative guidance, net of taxes							31,917	(31,917)	(31,917)
Net income (loss) attributable to XL Group plc								603,550	603,550
Change in net unrealized gains (losses) on investments, net of tax							997,066		932,769
Change in net unrealized gains (losses) on affiliate and other investments, net of tax							44,314		44,314
Change in OTTI losses recognized in other comprehensive income, net of tax							124,906
Change in underfunded pension liability							(2,619)		2,619
Change in value of cash flow hedge							439		(439)
Change in net unrealized gain (loss) on future policy benefit reserves							(3,714)		(3,714)
Foreign currency translation adjustments							50,953		50,953
Issuance of ordinary shares					0	1,109
Exercise of stock options					0				91
Buybacks of ordinary shares					(256)	(521,664)
Transfer to non-controlling interest in equity of consolidated subsidiaries				(10)		(999,990)
Dividends on preference ordinary shares						0		(34,694)
Gain on redemption of Redeemable Series C preference ordinary shares								16,616	16,616
Dividends on ordinary shares						0		(134,238)
Exercise of stock options, net of tax						1,182
Share based compensation expense						37,691
Non-controlling interests			4						39,831
Non-controlling interest share in change in AOCI			(13)
Transfer from Series E preference ordinary shares and additional paid in capital			1,000,000
Issuance of Series D preference ordinary shares			0
Purchase of preference ordinary shares	0	0
Balance at Dec. 31, 2010			1,002,296	0	3,165	8,993,016	100,795	513,777	10,613,049
Impact of adoption of new authoritative OTTI guidance, net of taxes							0	0	0
Impact of adoption of new authoritative embedded derivative guidance, net of taxes							0	0	0
Net income (loss) attributable to XL Group plc								(474,760)	(474,760)
Change in net unrealized gains (losses) on investments, net of tax							446,427		332,720
Change in net unrealized gains (losses) on affiliate and other investments, net of tax							25,269		25,269
Change in OTTI losses recognized in other comprehensive income, net of tax							39,456
Change in underfunded pension liability							(2,622)		2,622
Change in value of cash flow hedge							439		(439)
Change in net unrealized gain (loss) on future policy benefit reserves							0		0
Foreign currency translation adjustments							(26,700)		(26,700)
Issuance of ordinary shares					308	572,707
Exercise of stock options					1				72
Buybacks of ordinary shares					(317)	(666,705)
Transfer to non-controlling interest in equity of consolidated subsidiaries				0		0
Dividends on preference ordinary shares						0		0
Gain on redemption of Redeemable Series C preference ordinary shares								0	0
Dividends on ordinary shares						0		(138,978)
Exercise of stock options, net of tax						1,333
Share based compensation expense						38,327
Non-controlling interests			(83)						70,877
Non-controlling interest share in change in AOCI			(2,241)
Transfer from Series E preference ordinary shares and additional paid in capital			0
Issuance of Series D preference ordinary shares			350,000
Purchase of preference ordinary shares	(5,000)	(500)
Balance at Dec. 31, 2011			$ 1,344,472	$ 0	$ 3,157	$ 8,938,678	$ 583,064	$ (99,961)	$ 10,769,410